c83968575a
* Lazily populate a store's trampoline map This commit is another installment of "how fast can we make instantiation". Currently when instantiating a module with many function imports each function, typically from the host, is inserted into the store. This insertion process stores the `VMTrampoline` for the host function in a side table so it can be looked up later if the host function is called through the `Func` interface. This insertion process, however, involves a hash map insertion which can be relatively expensive at the scale of the rest of the instantiation process. The optimization implemented in this commit is to avoid inserting trampolines into the store at `Func`-insertion-time (aka instantiation time) and instead only lazily populate the map of trampolines when needed. The theory behind this is that almost all `Func` instances that are called indirectly from the host are actually wasm functions, not host-defined functions. This means that they already don't need to go through the map of host trampolines and can instead be looked up from the module they're defined in. With the assumed rarity of host functions making `lookup_trampoline` a bit slower seems ok. The `lookup_trampoline` function will now, on a miss from the wasm modules and `host_trampolines` map, lazily iterate over the functions within the store and insert trampolines into the `host_trampolines` map. This process will eventually reach something which matches the function provided because it should at least hit the same host function. The relevant `lookup_trampoline` now sports a new documentation block explaining all this as well for future readers. Concretely this commit speeds up instantiation of an empty module with 100 imports and ~80 unique signatures from 10.6us to 6.4us, a 40% improvement. * Review comments * Remove debug assert
wasmtime
A standalone runtime for WebAssembly
A Bytecode Alliance project
Guide | Contributing | Website | Chat
Installation
The Wasmtime CLI can be installed on Linux and macOS with a small install script:
$ curl https://wasmtime.dev/install.sh -sSf | bash
Windows or otherwise interested users can download installers and binaries directly from the GitHub Releases page.
Example
If you've got the Rust compiler installed then you can take some Rust source code:
fn main() {
println!("Hello, world!");
}
and compile/run it with:
$ rustup target add wasm32-wasi
$ rustc hello.rs --target wasm32-wasi
$ wasmtime hello.wasm
Hello, world!
Features
-
Lightweight. Wasmtime is a standalone runtime for WebAssembly that scales with your needs. It fits on tiny chips as well as makes use of huge servers. Wasmtime can be embedded into almost any application too.
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Fast. Wasmtime is built on the optimizing Cranelift code generator to quickly generate high-quality machine code at runtime.
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Configurable. Whether you need to precompile your wasm ahead of time, or interpret it at runtime, Wasmtime has you covered for all your wasm-executing needs.
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WASI. Wasmtime supports a rich set of APIs for interacting with the host environment through the WASI standard.
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Standards Compliant. Wasmtime passes the official WebAssembly test suite, implements the official C API of wasm, and implements future proposals to WebAssembly as well. Wasmtime developers are intimately engaged with the WebAssembly standards process all along the way too.
Language Support
You can use Wasmtime from a variety of different languages through embeddings of the implementation:
- Rust - the
wasmtimecrate - C - the
wasm.h,wasi.h, andwasmtime.hheaders or usewasmtimeConan package - [C++] - the
wasmtime-cpprepository or usewasmtime-cppConan package - Python - the
wasmtimePyPI package - .NET - the
WasmtimeNuGet package - Go - the
wasmtime-gorepository
Documentation
📚 Read the Wasmtime guide here! 📚
The wasmtime guide is the best starting point to learn about what Wasmtime can do for you or help answer your questions about Wasmtime. If you're curious in contributing to Wasmtime, it can also help you do that!
It's Wasmtime.